It is sometimes desirable in semiconductor device manufacturing to remove material from over discrete wafer areas, without exposing other wafer areas to the etchant solutions. One type of discrete area includes alignment marks which are used to align wafers during processing. Alignment marks are preferably kept substantially clear of contaminants or material so that processing equipment can easily locate them. Alignment marks can get covered with a variety of material including photoresist, etched substrate material, and chemical mechanical polishing slurry or a variety of thin films. When alignment marks get covered with material, it is desirable to remove the material. Methods and apparatuses for removing material from over alignment marks are described in U.S. Pat. No. 5,271,798, which is assigned to the assignee of this document, the disclosure of which is incorporated by reference.
This invention arose out of concerns associated with providing improved methods and apparatuses for removing material from discrete areas, e.g. alignment marks, on a semiconductor wafer.